KR19980041716A - Projection lens - Google Patents

Abstract

The present invention provides a projection lens for use with an LCD panel. This lens is concave with respect to each other and has two non-spherical meniscus components adjacent to the blockage of the lens and a color-corrected bilens that gives the positive optical power of most lenses.

The lens may contain a weak optical magnification non-spherical corrector lens component located on the side of two meniscus components facing the color corrected bilens.

Description

Projection lens

The present invention relates to a projection lens, and more particularly to a projection lens that can be used to form an image of an object composed of pixels, such as a liquid crystal display (LCD).

A projection lens system (hereinafter referred to as a projection system) is used to form an image of an object on a viewing screen. The basic structure of such a system is shown in FIG. 8, where 10 is a light source such as a tungsten-halogen lamp, and 12 is a light emitting element forming an image of the light source (hereinafter referred to as the output of the light emitting system). optics), 14 is the object being projected (i.e. matrix of on and off pixels of the LCD panel), and 13 is a projection lens composed of a plurality of lens components to display on the screen 16 An enlarged image of the object 14 is formed.

Projection lens systems whose objects are LCDs or other picelized panels are used in a variety of applications, including data display systems. Such a projection lens system preferably uses, for example, one single panel with red, green and blue pixels or one single projection lens which forms an image of three separate panels as one for each color. . In the following, the term projection lens system using a single LCD panel is used on the basis that the present invention can also be used in a system using multiple panels and / or other types of picelized products.

Projection lenses with a pixilated panel include United States Patent Publication, 4,189,211 (Taylor), United States Patent Publication 5,042,929 (Tanaka et al.), United States Patent Publication, 5,179,473 (Yano et al.), United States Patent Publication, 5,200,861 (Moscow Beach), United States Patent Publication, 5,218,480 (Moscow Beach), United States Patent Publication, 5,278,698 (Mizuka et al.), United States Patent Publication, 5,313,330 (Bettensk), United States Patent Publication, 5,331,462 (Yano).

An LCD system is disclosed in US Patent Publication No. 4,425,028 (Gagnon et al.), US Patent Publication No. 4,461,542 (Gagnon), US Patent Publication No. 4,826,311 (Redebur), and European Patent Publication No. 311,116.

The projection lens of the present invention consists of two strongly curved and symmetrical aspherical meniscus components, which have concave surfaces facing each other, which have weak power. It is desirable to have a color correcting doublet of positive power adjacent to the meniscus, i.e. with an aperture stop between the meniscus parts, before or after the parts. Have.

1 to 7 are side schematic views of projection lenses made in accordance with the present invention.

8 is a schematic diagram showing an overall projection lens system in which the projection lens of the present invention is used.

These projection lenses provide a sufficient degree of freedom to obtain a satisfactory correction of aberration of the lens. The non-spherical meniscus components largely contribute positively to the spherical, coma, and field curvature aberrations of the lens, canceling out the negative contributions resulting from the bi-lenses of high magnification. The color corrected bilens provides the necessary correction of chromatic aberration and the magnification of most lenses. Correction of astigmatism is achieved using a combination of non-spherical surfaces and the location of aperture stops for the magnification group. Another improvement to correct the distortion of the image is achieved using an additional non-spherical component, ie a corrector consisting of one or more lenses.

When non-spherical meniscus components are arranged on the object side of the color correction magnification bilens, the back focal length of the lens system as a whole tends to be approximately equal to or longer than the focal length of the system. On the other hand, if the magnification bilens is a leading component, the rear focal length of the system tends to be very small compared to the focal length of the system, so that the system gives a telephoto ratio of almost one.

The focal length of the magnification dual lens is always smaller than the absolute value of the focal length of each non-spherical meniscus part. The non-spherical Mejicus parts can be the same as each other. The price of these parts is very low when made of plastic, so that the entire lens can be economically produced in high volume production.

As will be explained in the following examples, the lens system has a maximum speed of f / 2.8 and a total angular coverage of about 50 degrees.

Description of the drawings and the following drawings constitutes a specification, but shows a preferred embodiment of the present invention, which helps explain the technical idea of the present invention, but the drawings and the description thereof are only intended to explain the present invention. The present invention is not intended to be limiting.

1 to 7 show several projection lenses made in accordance with the present invention. Applicable general and optical properties are in Tables 1 to 7, respectively. The name HOYA or SCHOTT was used for the glass used in the lens system. Equivalent glasses made by other manufacturers can also be used to practice the invention. Industrially applicable materials are used for styrene and acrylic parts. Aspheric coefficients described in the table are used in Equation I below.

Where z is the surface sag at a distance y from the optical axis of the system, C is the curvature of the lens at the optical axis and k is the conic constont.

Abbreviations used in the table are as follows.

EFL: effective focal length

FVD: front vertex distance

f /: f-unmber

ENP: entrance pupil

EXP: exit pupil

BRL: barrel length

OBJ HT: object height

MAG: magnification

STOP: location of aperture stop

IMD: image distance

OBD: object distance

OVL: overall length

In the table, the indication a with respect to various surfaces means a non-spherical surface, ie at least one of D, E, F, G, H or I in the above equation is non-zero surface. The designation c means a conical surface whose K value is not 0 in the above equation. Indication f means Fresnel lens surface. All figures in the table are in millimeters. The table is described on the assumption that the light goes from left to right in the figure. Practically the screen will be on the left, the LCD panel will be on the right and the light will go from right to left. Surface 11 in Table 5 is an artificial stop that causes the system to be telecentric on the short conjugate side of the Fresnel lens, and Surface 6 in Table 7 is the vignetting surface. to be.

Table 8 summarizes the various characteristics of the lens system of FIGS. 1 to 7. The overall focal length in the table does not include the Fresnel lens for FIGS. 5 to 7 because the lens basically only serves to couple the lens system to the illumination optics. The distance between menisci values in the table are measured between the outer surfaces (vertices) of the facing meniscus. The aperture stop position is the absolute value of the distance of the aperture blockage from the center point of the outer surface. The corrector focal length is for the leading lens component of FIG. 2 and the trailing lens component of FIGS. 5 to 7.

Table 8 shows that the dual lens is part of the most powerful system for all embodiments, in which the focal length is shorter than the focal length of all other components in the system. In addition, in the above table, except for Example 6, the menisici has a weak optical power, that is, the size ratio of the focal length of each meniscus to the total focal length of the system is less than 2.0. It is showing big. Similarly, the optical magnification of the compensator lens components used seems weak, ie, the ratio of the size of the focal length to the total focal length of the system is also greater than 2.0. The table also states that aperture stops are located between or near the meniscus (Examples 1 to 2 and 5 to 7) facing each other (Examples 3 to 4). The ratio of the distance from the center point of the outer surface of the meniscus to the distance between the outer surface is less than 0.60 (Example 4) and preferably less than 0.55 (Example 3) in the vicinity of the meniscus. Opening blockage is considered to be located.

The experiments of Tables 1 to 7 illustrate that another preferred form of projection lens of the present invention can be produced, namely one having a close space between the color-corrected bilens and the opposing meniscus. Preferably, the space is less than 0.3 times the total focal length of the projection lens. Similarly, the compensator lens component used is also required to have a space to be quite close to the facing meniscus, which space is preferably less than 0.3 times the total focal length of the projection lens.

Although embodiments of the present invention have been described and illustrated, those skilled in the art can be variously modified from the foregoing without departing from the scope of the present invention.

Table 5 Continued

Table 6 continued

Table 7 Continued

Example number Dual Lens Focal Length Meniscus 1 focal length Meniscus 2 focal length Compensation focal length Overall spill length Meniscus length Opening stop position One 98.38 -632.68 -632.68 119.05 45.76 10.22 2 95.73 -335.43 -335.43 262.79 119.00 45.60 1.46 3 160.30 558.66 558.66 119.00 31.15 17.12 4 178.65 451.09 451.09 119.00 34.74 19.69 5 102.11 -340.67 -340.67 276.64 119.01 30.43 7.26 6 193.80 214.60 214.60 -315.01 119.00 25.49 5.96 7 108.36 -805.14 -805.14 654.50 119.00 26.44 9.05

Claims (21)

A projection lens for forming an image of an object having an opening clogging and consisting of the following (a) and (b). (a) consisting of two meniscus parts having focal lengths f1 and f2, the meniscus parts being (i) concave with respect to each other and (ii) located adjacent to the opening blockage, The varnish part comprises a first lens unit having at least one non-spherical surface; And (b) f 3 0; f3 | f1 |; And f3 | f2 | Second lens unit consisting of a color-corrected bifocal with a focal length f3 The projection lens of claim 1, wherein each meniscus component has a weak optical power. The projection lens of claim 1, wherein each meniscus component is the same. The projection lens of claim 1, wherein each meniscus component has two aspheric surfaces. The projection lens of claim 1, wherein the opening blockage is located between the two meniscus parts. The projection lens of claim 1, wherein the first lens unit is on the image side of the lens and the second lens is on the object side of the lens. The projection lens according to claim 1, wherein the first lens unit is on the object side of the lens and the second lens unit is on the image side of the lens. The projection lens of claim 1, wherein the first and second lenses are in close proximity to one another. 2. The compensator lens unit of claim 1, comprising (i) at least one non-spherical surface, (ii) weak optical magnification, and (iii) located on the side of the first lens unit opposite the second lens unit. Projection lens included more. 10. The projection lens according to claim 9, wherein said corrector lens unit is composed of one single lens component. 10. The projection lens of claim 9, wherein the compensator lens unit is composed of two non-spherical surfaces. 12. The projection lens of claim 11, wherein the compensator lens unit is composed of one single lens component. 10. The projection lens according to claim 9, wherein said corrector lens unit is on the image side of said first lens unit. 10. The projection lens according to claim 9, wherein the corrector lens unit is on the object side of the first lens unit. 10. The projection lens according to claim 9, wherein said corrector lens unit is spaced in proximity to said first lens unit. 10. The projection lens of claim 9, wherein f1 and f2 have the same sign, the compensator lens unit has a focal length f _CR , and the sign of f _CR is opposite to the sign of f1 and f2. A projection lens for forming an image of an object having an opening clogging and consisting of the following (a) and (b). (a) two meniscus parts having focal lengths f1 and f2, (iii) concave with respect to each other, (ii) adjacent to said opening block, and having two non-spherical surfaces, and (b) f 3 0; f3 | f1 |; And f3 | f2 | Color-corrected bifocal with in focal length f3 A projection lens for forming an image of an object having an opening clogging and consisting of the following (a), (b) and (c). (a) two meniscus parts having focal lengths f1 and f2, (iii) concave with respect to each other and (ii) adjacent to said opening block and having two non-spherical surfaces, Δ (b) f 3 0; f3 | f1 |; And color corrected bilens with a focal length f3 of f3 | And (c) a compensator lens part having two non-spherical surfaces and of low optical magnification, wherein the color corrected bilens and the compensator lens part are on opposite axes of the two meniscus parts. Next, a projection lens system for forming an image of the object consisting of (a), (b) and (c), (a) a light source comprising a light source and a light emitting element for forming an image of the light source, the image of the light source being the focal point of the light emitting system; (b) a picelized panel constituting the subject; And (c) the projection lens of claim 1 Next, a projection lens system for forming an image of the object consisting of (a), (b) and (c), (a) a light source comprising a light source and a light emitting element for forming an image of the light source, the image of the light source being the focal point of the light emitting system; (b) a picelized panel constituting the subject; And (c) the projection lens of claim 17 Next, a projection lens system for forming an image of the object consisting of (a), (b) and (c), (a) a light source comprising a light source and a light emitting element for forming an image of the light source, the image of the light source being the focal point of the light emitting system; (b) a picelized panel constituting the subject; And (c) the projection lens of claim 18